During the past decade, researchers in the U.S. and other countries have reported an increase in the prevalence of mild to moderate enamel fluorosis in both fluoridated and non-fluoridated areas. Few analytical epidemiologic studies have been performed to identify fluorosis risk factors. Recent research indicates that exposure to fluoride supplements during the early years of life is strongly associated with mild to moderate enamel fluorosis and that the 1978 downward revision of only the first two years of the fluoride schedule may be inadequate to prevent fluorosis in successive supplemented populations. Research has also suggested fluoride dentifrice use as a possible risk factor of enamel fluorosis. The purpose of this proposed research is to determine the association between enamel fluorosis and (1) fluoride supplementation under the revised schedule and (2) early fluoride dentifrice use in a 1980-81 cohort of 12-13 year old children who are life-long residents of a non-fluoridated area. This research will also determine the association between enamel fluorosis and early fluoride dentifrice use and infant diet among two fluoridated cohorts of 12-13 year old children, (1) a 1976-77 cohort who have ingested formula prior to industry's voluntary removal of fluoride, and (2) a 1980-81 cohort who would have ingested formula after the start of the practice of removing fluoride. A case-control design will be used, based on a previously successful model. Cases and controls will be determined by clinical examination. A mailed questionnaire, completed and returned by the parents of subjects, blind to their child's diagnosis will identify past fluoride exposures. Multiple logistic regression analysis and the Mantel-Haenszel odds ratio and Chi Square Statistic will be used to estimate the relative risk of enamel fluorosis associated with each exposure adjusted for the confounding effects of other exposures. The results of this study will contribute to a pool of knowledge which will allow the optimum therapeutic balance point demonstrated fifty years ago by Dean, where there is a maximum carries preventive efficacy with a minimal risk of fluorosis to be restored.